Abstract:

CFC replacement solvent compositions, methods of using the same and
methods of making the same. These compositions meet or exceed the
solvency, flammability, and compatibility requirements for CFC's while
providing similar or improved environmental and toxicological properties.
These solvent compositions have applications including, but not limited
to, oxygen handling, refrigeration or heat pumps, electronics,
implantable prosthetic devices, and optical equipment.

Claims:

1. A method for increasing the solubility range of a solvent used to clean
or degrease oxygen handling systems, refrigeration systems, implantable
prosthetic devices, electronics, or optical equipment, said method
comprising the steps of:(1) providing a first compound selected from the
group consisting of fluorinated alkanes, diones, heterocyclics,
cycloalkanes, anhydrides, ketones, cycloalkenes, aromatics, acetates,
ethers, esters, alcohols, and alkenes; and a second compound which
contains one bromine atom and is selected from the group consisting of
partially fluorinated aromatics, ketones, ethers, and alkenes; and(2)
mixing the first and second compound to obtain the solvent with increased
solvency range.

3. The method of claim 1, wherein said second compound comprises at least
one compound selected for the group consisting of
4-bromo-3-chloro-3,4,4-trifluoro-1-butene,
1-bromo-2-(trifluoromethyl)-3,3,3-trifluoropropene, and
4-bromo-3,3,4,4-tetrafluoro-1-butene.

Description:

RELATED APPLICATIONS

[0001]This application is a divisional application of U.S. application
Ser. No. 11/043,091, filed Jan. 27, 2005, the disclosure of which is
incorporated by reference herein.

[0002]This application is related to "Replacement Solvents Having Improved
Properties and Methods of Using the Same" filed on even date, which
serial number is not yet assigned but is referenced by attorney docket
number 029211.55582D1 by attorneys for Applicants.

BACKGROUND OF THE INVENTION

[0004]Chlorofluorocarbons (CFC's) are widely used solvents for precision
cleaning of parts and components due to their superior physical and
chemical properties, especially their solvency for contaminating
materials such as oils, greases, resin fluxes, particulates, and other
contaminates. One solvent commonly used in many applications is CFC-113
(1,1,2-trichloro-1,2,2-trifluoroethane). These solvents are used to clean
and/or degrease components or systems related to, but not limited to,
oxygen handling systems, refrigeration equipments or heat pumps,
electronics, implantable prosthetic devices, and optical equipment. In
addition, these solvents have been used as a means to measure residue
remaining is a system. For example, in Air Force launch vehicle
applications involving liquid or gaseous oxygen systems, CFC-113 was the
solvent of choice used to detect and quantify the amount of hydrocarbon
and fluorocarbon residues in these systems, since the presence of those
contaminants can be catastrophic. A further application of these solvents
is for foam blowing and polymer coating.

[0005]CFC-113 has many favorable characteristics such as low toxicity;
non-flammability; and stability. Furthermore, CFC-113 is not classified
as an air-polluting volatile organic compounds (VOC's) by environmental
regulators, is practically odorless, and has a high worker exposure
threshold value, eliminating the need for costly air circulation or
dilution precautions. These benefits also came at a low price (less than
1% of total manufacturing costs in 1988). Coupled with the growth of the
electronics industry, and concerns over worker safety due to toxic
chemical exposure and hazardous waste disposal resulting from the use of
VOC's, the desirable characteristics led to the widespread use of
CFC-113.

[0006]With the rise of electronic equipment during the 1970s, the need to
properly clean these contaminant sensitive parts became very important
and the solvent, 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113), was
found to be an excellent and versatile solvent. Being able to dissolve an
unusually large array of contaminants (greases, oils, etc) and having
excellent physical characteristics, CFC-113 became the
`solvent-of-choice` for electronics cleaning and it's use spread to other
applications--especially military. Specifically, CFC-113 was used to
remove solder flux from small spaces between electronic components so as
to ensure adhesion of coatings, and prevent corrosion and
electromigration of ions. Even more favorable were the non-aggressive
properties of CFC-113 towards most polymers and coatings and its use
permitted a wide use of plastics and other solvent-sensitive materials in
the manufacture of electronic components. By 1986, the removal of solder
flux from printed circuit board assemblies accounted for close to half of
worldwide CFC-113 consumption. A significant portion of the remaining
half was utilized by the military and in particular, aviation.

[0007]The use of CFC-113, however, is restricted due to the Montreal
Protocol due to its ability to react and deplete atmospheric ozone. By
the Mid 1980s, problems regarding the ozone became apparent and the
primary culprits were certain halogenated hydrocarbons including CFC-113.
In 1987, twenty-four nations agreed in principle to control
ozone-depleting substances (ODS), such as CFC-113. Although this solvent
had become critical to the electronics industry, the importance of
protecting the earth's ozone layer weighed heavier. Thus, non-toxic and
non-ozone depleting replacement solvents became a priority for
electronics manufacturers and the military. Various CFC-113 substitutes
have emerged and often rely on solvents such as n-propyl bromide and
dichloroethylene, which are flammable and not as desirable as CFC-113.

[0008]Refrigeration systems also require periodic flushing to remove
contaminants. A contaminated refrigeration system may have drastically
reduced performance resulting from compressor failure, for example. The
materials and contaminants in these systems differ from other
applications and therefore solvents must be optimized accordingly. For
example, a flushing solvent must be compatible with the elastomers and
metals in typical systems, while at the same time have the solvency
properties to remove oils, acids, and decomposition products of the oils
and refrigerants. Some of the currently used flushing solvents include
terpenes (e.g., d-limonene), n-propyl bromide, pentafluorobutane,
HCFC-141b, and HCFC-225 ca/cb.

[0009]Selection for CFC replacements typically involves two steps. First,
commercially available materials with limited impact on the environment
are selected; these are termed next-generation replacements. These
next-generation replacements are interim and do not have all the desired
properties of an ideal replacement (e.g. they are not as effective
solvents or have non-zero ozone depletion potentials, or ODP). The second
step is to evaluate the so-called second-generation replacements that are
not commercially available, but are only available in research quantities
or by custom synthesis, and have properties that are not known.
Evaluation and manipulation (e.g. by mixing) of these candidate second
generation solvents will result in second generation replacements that
meet or exceed the next generation solvents' overall performance since
all critical properties required of the solvent are accounted for.

[0011]The solvency of the replacement should be comparable to CFC so the
primary factor of performance is not compromised. The volatility and
materials compatibility of the replacement solvent should be similar to
the CFC so there is minimal impact on existing cleaning systems by
switching solvents. Hazardous risks such as flammability, toxicity, and
environmental impact are also critical since every manufacturer will be
required to eliminate hazardous solvents in the near future.

[0012]The solvency performance of the candidate replacements can be
quantified through the solubility parameter of the compounds. The hazard
potential of the candidate replacements can be characterized using
toxicity information such as lethal doses (LD), lethal concentrations
(LC) or threshold limit values (TLV), and flammability information.
Environmental properties can be analyzed through ozone depletion
potential (ODP), global warming potential (GWP), and tropospheric
lifetime (TLT). For a discussion of these parameters and their
measurements or calculations, see e.g. U.S. Pat. No. 6,300,378, to
Tapscott. Volatility can be assessed using the normal boiling point (nBP)
of the solvent. If all of these properties and others can be
experimentally measured or modeled, one could identify and test
non-hazardous "drop-in" replacement solvents to replace hazardous
solvents. The following paragraphs discuss the relevance of these
performance parameters.

Cleaning Effectiveness or Solvency

[0013]The solubility parameter is a very important measure of the cleaning
effectiveness of a solvent in dissolving and removing another material.
In general, these parameters provide an easy numerical method of rapidly
predicting the extent of interaction between materials, particularly
liquids. Compounds with similar solubility parameters are known by those
skilled in the art to have similar solvency properties. For example,
CFC-113 has a solubility parameter or about 7.5 which is within the range
where a solvent will dissolve both hydrocarbon and fluorocarbon greases.
This is a fairly unique solubility parameter and is a major part of what
makes CFC-113 such an excellent solvent. It also makes the substitution
for CFC-113 rather difficult.

[0014]A quantitative method for comparing the relative solubility of
different materials is through the use of solubility parameters. This
concept of expressing solubility is based on the idea that the solution
of one material in another is a spontaneous process, and that it can be
stated in terms of the free energy of mixing as shown below:

ΔG=ΔH+TΔS, (1)

where ΔG is the free energy of mixing, ΔH is the enthalpy of
mixing, and ΔS is the entropy of mixing. The controlling term for a
spontaneous process (where ΔG is negative) is the enthalpy of
mixing, which can be expressed in terms of x1 and x2, the mole
fraction of the components, V1 and V2, the molar volumes, and
a1 and a2, the interaction constants.

[0015]The expressions for the enthalpy and entropy of mixing are given
below:

Δ Δ ##EQU00001##

[0016]The cohesive energy of a mole of a liquid mixture can be stated as

Δ Δ Δ φ φ ##EQU00002##

where ΔE.sup.υ is the energy of vaporization and φ1
and φ2 are volume fractions. The enthalpy of mixing can be
rewritten as

Δ Δ Δ φ φ ##EQU00003##

where the term ΔE.sup.υ/V, the energy of vaporization per
unit volume, is a measure of the internal pressure.

[0017]This term is called the solubility parameter, δ, and is
defined below:

δΔ Δ ##EQU00004##

where ΔH.sup.υ is the latent heat of vaporization. (The
units of the solubility parameter are typically expressed in
(cal/cm3)1/2).

[0018]Therefore, the free energy of mixing is given by:

ΔG=V[δ1-δ2]φ1φ2+RT[x1+x-
2 ln x2] (7)

and solution should occur as δ1 approaches δ2.

[0019]The above expression shows that the solubility parameter of a
compound can be calculated directly from the latent heat of vaporization
and the molar volume of the compound if these are available. Regardless
of the method of determination, solubility parameters are useful in
comparing the solvency of compounds because solvents with similar
solubility parameters are known by those skilled in the art to have
similar solvency properties.

[0021]The volatility of a replacement solvent can be described in terms of
properties such as the normal boiling point (nBP). An effective solvent
replacement must be volatile enough to evaporate, but should not flash
off of surfaces since the solvent must reside on the contaminants long
enough to dissolve them. An nBP around 40° C. or higher is
generally acceptable for cleaning applications.

Compatibility

[0022]Material and system compatibility is another requirement for a
second-generation solvent. The solvent must be compatible with metals
such as aluminum, copper, carbon steel and stainless steel, as well as
elastomers. The solvent should not degrade or corrode surfaces in the
system being cleaned. The solvent also needs to be compatible with the
particular system application. For example, a solvent to be used for
cleaning oxygen handling system must be compatible with liquid and
gaseous oxygen. In this case, tests such as ASTM G86 for ignition
sensitivity to mechanical impact must be considered.

Flammability: Autoignition, Flashpoint

[0023]Whether a solvent is suitable as cleaning solvents for systems
(e.g., oxygen handling systems) is partially dependent upon its
flammability, which sometimes is quantified by the autogenous ignition
temperatures (AIT). AIT provides a measure of the material's relative
ease of ignition and indicates the approximate temperature at which a
material could be expected to spontaneously ignite in high-pressure
oxygen. This test is typically performed per ASTM Method G72. A rating
system has been established by the NASA White Sands Test Facility and
Wright-Patterson Air Force Base. By this system, compounds are classified
as A (not recommended, AIT<250° F.), B (caution when used,
250° F.<AIT<400° F.), and C (recommended,
AIT>400° F.).

[0024]Another aspect of the flammability determination is the flashpoint
of the solvent. The flashpoint is the temperature at which a liquid gives
off vapor sufficient to form an ignitable mixture with air (oxygen) near
the surface of the liquid. The ideal replacement solvent should not have
a flashpoint below or at its boiling point. This insures a wide range of
conditions whereby the solvent can be safely used.

Environmental Persistence

[0025]The environmental persistence of a solvent is also very important.
Parameters such as the ozone depletion potential (ODP), global warming
potential (GWP), and tropospheric lifetime (TLT) are measures of this
attribute. ODP and GWP give the relative ability by weight of a chemical
to deplete stratospheric ozone and to contribute to global warming,
respectively. Values for ODP, GWP and TLT are calculated based on an
earth surface release and then reported relative to a reference compound
(typically CFC-11 for ODP and CFC-11 or carbon dioxide for GWP).
Generally, the ODP should be less than 0.02, and the GWP and TLT should
be minimized, preferably lower than the solvent being replaced.

[0026]The biochemical oxygen demand (BOD) is also another measure of
persistence typically in groundwater, lakes, and other bodies of water.

Toxicity

[0027]Toxicity is yet another factor which must be considered when
selecting second-generation replacement solvents. Parameters such as the
lethal dose 50 (LD50), lethal concentration 50 (LC50), cardiac
sensitization, skin irritation, and mutagenicity (e.g., via the Ames
test) can be used as measures. LDn or LCn abbreviation, where n is the
percent lethality, is used for the dose of a toxicant lethal to n % of a
test population. For instance, at LD50, 50% of the recipients of that
particular toxic dose would die. Cardiac sensitization is a measure of
the ability of a compound to cause cardiac arrhythmia under stress.
Generally, it is desired to minimize these parameters and select
compounds that have lower values than the solvent that is being replaced.

Review of Prior Art

[0028]The CFC-113 replacements known in prior art do not address all of
the required second-generation solvent properties. CFC-113 replacements
and solvents that address ozone depletion have been introduced and are
disclosed in e.g. U.S. Pat. Nos. 5,035,828, 6,402,857, 6,297,308, and
6,020,298. Various solvents and solvent mixtures are disclosed which have
low ODPs. These replacement solvents, however, do not possess all of the
desired properties of CFC-113 such as flammability, toxicity, oxygen
compatibility and cleaning effectiveness.

[0029]In U.S. Pat. No. 5,035,828, HCFC-234 is combined with an aliphatic
alcohol or cyclohexane, but this mixture is easily flammable. U.S. Pat.
No. 6,402,857 utilizes n-propyl bromide with other organic constituents,
which are also flammable and have a significant adverse impact on ozone.
U.S. Pat. No. 6,020,298 utilizes hydrofluoropolyethers, and U.S. Pat. No.
6,297,308 utilizes halogenated ethers and hydrocarbons with a surfactant.
While these solvents appear to avoid damage to the ozone layer, the
perfluorinated compounds contained therein are known to be potent
greenhouse gases. In addition, perfluorinated and fluorinated (no
chlorine) solvents are undesirable as they can have widely varying
solubility properties and different interactions with organic residues
when compared to CFC-113.

[0030]U.S. Pat. No. 6,103,684 teaches the use of azeotrope-like mixtures
comprised of 1-bromopropane with non-halogenated alcohols and alkanes, as
well as halogenated alkanes and fluorinated ethers. The ODP for
1-bromopropane is stated as being between 0.002 and 0.03, classifying it
as a Class II Ozone Depleting Substance. The flammability limits of
1-bromopropane are 2.7-9.2% in air, with an auto-ignition temperature of
490° C. In addition, the solubility parameter of 1-bromopropane is
also 8.839, too high to effectively dissolve many greases and oils.
Furthermore, the alcohols and alkanes of this invention are also
flammable.

[0031]In U.S. Pat. No. 6,048,832, the inventors disclose the use of
1-bromopropane with 4-methoxy-1,1,1,2,2,3,3,4,4-nonafluorobutane (an
ether) and at least one other non-halogenated organic compound. As in
U.S. Pat. No. 6,103,684, the use of 1-bromopropane is questionable due to
its high ODP, flammability, and undesirable solubility parameter. The
other components, such as ethanol and 2-propanol, also have high
solubility parameters of about 11-13, thereby decreasing the usefulness
of these mixtures for a broad spectrum of contaminants as will be taught
by the present invention.

[0032]Solvents that meet the environmental restrictions and are
non-flammable are disclosed in U.S. Pat. Nos. 6,300,378 and 5,759,430 and
in Tapscott & Mather, 2000, Tropodegradable fluorocarbon replacements for
ozone-depleting and global-warming chemicals. J. Fluorine Chemistry
101:209-213. Compounds disclosed therein are generally non-flammable
and/or non-ozone depleting, as they are "tropodegradable fluorocarbons,"
defined as compounds having structural weaknesses to ensure rapid decay
in the troposphere. When this class of compounds is exposed to sunlight
(photolysis) or chemical radicals (e.g. hydroxyls) in the atmosphere,
they decay into forms that do not damage the ozone layer nor contribute
to the greenhouse effect. The structural weaknesses can take such forms
as hydrogen being present on the molecule, a carbon-carbon double bond
that is vulnerable to reactions, an ether bond, or a bromine atom being
present for easy degradation. These structural vulnerabilities render the
molecules unstable, and within a fairly short period of time, they break
down and are no longer part of the atmosphere. These references, however,
fail to teach solvents with optimized solubility parameters, together
with desirable toxicity, and material compatibility. Specifically, these
references do not suggest any advantages of using chlorine-containing
ethers.

[0034]U.S. Pat. No. 4,999,127 teaches an azeotropic mixture of
CHF2--CClF-O--CHF2, trans-1,2-dichloroethylene, and methanol.
Some components of this mixture are toxic and flammable, and hence, not
desirable as a safe second generation solvent replacement.

[0035]In short, the prior art has taught replacements to CFC's which only
partially meet the requirements of a second generation solvent. There is
thus a need for second generation replacement solvents that possess all
required performance parameters.

SUMMARY OF THE INVENTION

[0036]This invention provides second generation solvents that possess all
important performance properties, including:

[0044]We have discovered that mixtures of certain halogenated compounds
can meet or exceed the performance properties of CFC's, and in
particular, CFC-113. These solvent mixtures comprise two or more
compounds selected from hydrofluorochloro-ethers (HFCE's),
hydrobromochlorofluoro-alkenes (HBCFA's), hydrofluoro-ethers (HFE's), and
halogenated alkanes, alcohols, diones, acetates, ketones (e.g.,
butanones, pentanones), esters (e.g., propanoates), anhydrides,
cycloalkanes (cycloparaffins), cycloalkenes (cycloolefins), heterocyclics
(e.g., furans), and aromatics. Many of these compounds have been ignored
in the past based on an incomplete evaluation and assumption of
generalities pertaining to performance properties. Our approach to
identifying these optimal solvent mixtures utilized quantitative
structure property relations (QSPR's) and a complex ranking scheme to
objectively and completely evaluate numerous potential candidates and
numerous properties required to meet the performance of CFC solvents.
Many of the compounds and mixtures discovered through this process are
novel and have not been considered in the prior art.

[0045]The mixtures taught by this invention comprise compounds which are
non-flammable as measured by flashpoint and AIT testing, have ODP's of
less than about 0.02, and have solubility parameters within about 10% of
CFC-113. The boiling points of these components and mixtures are also
greater than about 40° C. to make them useful in most solvent
applications, with toxicities less than or similar to CFC-113. We have
also found that these components and mixtures are compatible with most
elastomers and metals.

[0046]One object of the present invention is to teach CFC solvent
replacements comprising at least two tropodegradable components that act
collectively to: meet or exceed the cleaning effectiveness or solvency of
the CFC targeted for replacement; have ODP values less than about 0.02;
have boiling points greater than about 40° C.; have toxicities
less than or similar to the CFC targeted for replacement; have no flash
point up to their boiling point; have autogenous ignition temperature
classifications of B or C, and be compatible with common elastomers and
metals.

[0047]The present invention further discloses that certain brominated
compounds can be included in solvent mixtures to affect solvency
properties so as to perform similar to or better than the CFC targeted
for replacement. These brominated compounds are known to offer reductions
in flammability, but we have discovered surprisingly that they also offer
effective CFC solvency enhancement when combined with other compounds.

[0048]It has also been surprising discovered that mixtures of certain
compounds can effectively increase the solvency range for certain common
contaminants (e.g., hydrocarbon and fluorocarbon greases, oils,
decomposition products) when compared to the CFCs targeted for
replacement.

[0049]In another aspect, this invention shows that compounds that have
generally been used as anesthetics are excellent solvents which possess
minimal or well-characterized toxicity.

[0050]Yet another object of this invention is to teach the use of second
generation solvent mixtures to clean and/or degrease components or
systems related to, but not limited to, oxygen handling systems,
refrigeration systems or heat pumps, electronics, implantable prosthetic
devices, and optical equipments.

[0051]In a preferred embodiment, solvent mixtures of the present invention
are compatible with liquid oxygen handling systems, especially with
regard to ignition sensitivity to mechanical impact in liquid oxygen.

[0052]A related object of this invention is to teach alternative CFC
compositions suitable for foam blowing and applying coatings.

[0053]An additional object of this invention is to teach the general
methods by which second generation solvents can be specified to replace
not only CFC's, but also future compounds which will be banned from use
such as hydrochlorofluorocarbons (HCFC's) and hydrobromofluorocarbons
(HBFC's).

BRIEF DESCRIPTION OF TABLES 1 AND 2

[0054]Table 1 lists compounds derived using the methods of the present
invention. Compounds listed therein have boiling points greater than
40° C., ODP values less than about 0.02, a solubility parameter
within a range of about +10% of CFC-113, a CS value greater than or equal
to 80% of the CFC-113 value, and TLT's less than that of CFC-113. In
Table 1, CS/CS113 refers to cardiac sensitization (CS), a measure of
inhalation toxicity of the compound relative to CFC-113 with a predicted
value of 1090 ppm; and SP is the solubility parameter. The values for
this selected group of solvent properties are shown with CFC-113 as
reference. Five more preferred compounds of this invention are denoted by
the letters A though E in the table. The underlined numbers in Table 1
are experimental values. Others are predictions from quantitative
structure property relations (QSPR's, see below), illustrating the
necessity of using QSPR's as taught by this invention to compare and
evaluate a large list of second-generation candidates.

[0055]Table 2 summarizes some of the preferred compounds, and their
boiling points and solubility parameters relative to CFC-113.

DETAILED DESCRIPTION OF THE INVENTION

[0056]The solvent CFC-113 (1,1,2-trichloro-1,2,2-trifluoroethane) had been
the solvent of choice for many applications until the mid-1980's. Due to
its phase out, alternative solvents with similar overall properties have
been sought. Those skilled in the art have attempted to find replacements
with some success, believing that because CFC-113 possess so many
desirable properties that must be matched, a replacement solvent must
sacrifice or comprise on some performance properties.

[0057]Using a novel and heretofore never suggested approach, the inventors
of the present invention first developed a comprehensive list of
candidate replacements meeting key performance properties, and then
tested these individual components as replacements. This approach is
completely objective and unbiased by previously untested assumptions or
generalities related to certain classes of compounds.

[0058]As a consequence, the inventors of the present invention discovered,
as have others, that a single component replacement cannot meet all of
the performance requirements of most first generation solvents, most
notably, solvency. Our focus then turned to mixtures of compounds which
possessed a difference in solubility parameter in order to increase the
solubility range for the second generation solvent. It is by this process
that we discovered certain synergies when combining these solvents. The
general process by which we made this discovery is described below.

[0059]We considered a total of about 800 compounds. The compounds included
halogenated alcohols, halogenated alkenes, halogenated amines,
halogenated aromatics, halogenated carbonyls, halogenated ethers,
halogenated alkanes, halogenated heterocyclics, halogenated cycloalkanes
(cycloparaffins), and halogenated cycloalkenes (cycloolefins). The list
of potential second-generation CFC solvent replacements was then
mathematically analyzed to arrive at a list of compounds which
simultaneously met the performance requirements for solvency, boiling
point, and toxicity for a second-generation replacement to CFC-113. A
mathematical database of properties critical to solvent function was
tabulated with this large list of potential second generation solvents.
If literature or experimental values for the performance properties were
not available, we developed quantitative structure property relations
(QSPR's) to model and predict the particular property which was then
included in the database table. Those skilled in the art will understand
the usefulness and accuracy of QSPR's in the development of products such
as environmentally-friendly chemicals and pharmaceuticals. This overall
method of objectively selecting compounds by considering a large number
of constraining performance properties can be used for a variety of
applications whereby target properties of the first generation solvent
are known.

[0068]Of the properties listed above, those having primary significance in
selecting a second generation replacement are the solvency, volatility,
toxicity, and environmental persistence. More specifically, an acceptable
second generation solvent should generally have boiling points greater
than about 40° C., ODP values less than about 0.02, high LD50
values greater than about 5 g/kg, and solubility parameters within about
10% of CFC-113. Other toxicity measures (e.g., cardiac sensitization or
CS, mutagenicity, skin irritation, and inhalation LC50) should be
minimized with respect to the compounds targeted for replacement. The
remaining properties of compatibility and flammability are also
important, and were measured for several compounds meeting the solvency,
volatility, toxicity, and environmental persistence requirements. Table 1
shows a summary of numerous compounds resulting from the process
described above which met these important performance properties. The
values in underlined are experimental data, whereas the other values are
QSPR model predictions. CFC-113 properties are shown on line 1 of Table 1
for comparison.

[0069]In general, the compounds of Table 1 are halogenated acetates,
alcohols, alkanes, alkenes, anhydrides, aromatics, cycloalkanes,
cycloalkenes, diones, esters, ethers, heterocyclics, or ketones, with or
without the heteroatom bromine. Aside from these compounds meeting the
other required properties for CFC-113 replacement, the presence of
bromine also has the effect of reducing flammability, although this
invention does not require a bromine atom be present to reduce
flammability. We have found that the compounds most useful for
second-generation solvent replacements of CFC-113 have the following
chemical formula: CqHrBr.sub.xClyFzO.sub.p, where
q=3-10, r=0-11, x=0-1, y=0-2, z>1, and p=0-3. Many of these compounds
belong to the classes of hydrofluorochloro-ethers (HFCE's),
hydrobromofluorochloro-alkenes (HBFCA's), and hydrofluoro-ethers (HFE's).
This formula also incorporates compounds in the families of alkanes,
alcohols, diones, acetates, ketones (e.g., butanones, pentanones), esters
(e.g., propanoates), anhydrides, cycloalkanes (cycloparaffins),
cycloalkenes (cycloolefins), heterocyclics (e.g., furans), and aromatics.
As illustrated in Table 1, all of them meet the performance requirements
detailed in this invention.

[0071]Using the further restriction of cost and availability on the
compounds, we identified in Table 1, some of the preferred compounds of
this invention that are viable CFC-113 replacements, including:

[0077]Compound B above is also known as isoflurane, and compound C is
known as enflurane, both common anesthetics. These preferred compounds of
our invention for CFC-113 replacements have boiling points greater than
about 40° C., solubility parameters within about 10% of CFC-113,
ODP values less than about 0.02, lower TLT and GWP than CFC-113, and
minimal toxicity lower than that of CFC-113. Of particular utility in
this invention are HFCE's, previously overlooked by those skilled in the
art, when combined with other halogenated ethers and/or halogenated
alkenes. The use of anesthetics compounds also has advantages in that
they have been thoroughly tested for toxicity by the medical community,
and these compounds will be more easily and more quickly accepted as
alternative solvents.

[0078]Note that the ODP for CFC-113 is much higher than 0.02, classifying
it as a Class II Ozone Depleting Substance. The GWP and TLT of CFC-113
are also 5000 and 0.9, respectively. The toxicity of CFC-113 is also
typically higher than those compounds shown in Table 1. Some of the
compounds identified by this approach and listed in Table 1 have many
properties improved over CFC-113 while having the same or similar
solvency properties, (e.g., solubility parameter within 10% of CFC-113).

[0079]We then proceeded to verify the primary performance properties
(e.g., solvency toward different contaminants such as oils and greases)
of the compounds specified by this invention. The solvency properties of
the compounds taught by this invention have been verified for compounds
typically found in applications, such as oxygen handling systems and
refrigeration system flushing. For example, certain oils, greases and
cleaners such as Mil-spec 83232 hydraulic oil, Mil-spec 7808 engine oil,
Mil-spec 81322 hydrocarbon grease, Krytox, and Simple Green are used in
oxygen handling systems. The compounds listed above have been found to
dissolve some of these contaminants, and when used in mixtures a broader
range of contaminant types can be dissolved.

[0080]We then discovered that although some of these replacements
identified and listed in Table 1 can meet or exceed some of the
performance properties of CFC-113, the solvency toward a variety of
greases and contaminants was inferior to CFC-113 and other single
component second generation compounds. Further, we discovered that by
combining 2 or more of these identified compounds, solvent blends can be
tailored to provide optimized solvency toward a range of contaminant
types. In fact, the combination of 2 or more solvents can provide
improved solvency toward contaminants such as greases and oils since the
solvency range can be extended or broadened when compared to a single
compound. This also suggests that synergies exist when combining
compounds identified in this invention would not have been expected if
considering only the individual components of the mixture It must also be
recognized that the solvency of the 2 or more compounds comprising the
solvent must be similar, otherwise the 2 or more components will not be
soluble in each other.

[0081]The advantage of using mixtures which increase the solubility range
of the solvent replacement can be appreciated when considering the
solubility parameters. The solubility parameter of CFC-113 is 7.2. The
solubility parameter necessary to dissolve both fluorocarbon and
hydrocarbon grease in oxygen systems has been found to be somewhere
between 7.5 and 7.7. In general, values less than 7.5 favors dissolution
of fluorocarbon but not hydrocarbon greases whereas values in excess of
7.7 tend to favor the opposite. Hence, the advantages to using the
approach taught by this invention provides for improved and more
versatile solvents that can not only dissolve a wide range of contaminant
types, but they also meet the many other requirements placed on solvents
such as environmental persistence, toxicity, and material compatibility.
For example, by combining the two compounds, (A.)
4-bromo-3-chloro-3,4,4-trifluoro-1-butene and (B.)
1-chloro-2,2,2-trifluoroethyl difluoromethyl ether (aka isoflurane), the
solubility parameter will still be between the values 7.65 and 7.7 and is
shown to effectively dissolve both types of grease contaminants in an
oxygen handling system.

[0082]We then proceeded to characterize other properties such as
compatibility, flash point, and autogenous ignition temperature. We
discovered that, contrary to commonly held beliefs, it is not necessary
for the compound or the mixture to contain bromine heteroatoms in order
to possess desirable flammability properties. In fact, some of the tested
compounds exhibited AIT temperatures categorized as "C", or recommended
for oxygen systems. We have also discovered that several of the compounds
we have identified using the methods taught by this invention also have
no flashpoints up to the boiling point of the compound.

[0083]This invention also teaches that a bromine-containing compound is
not necessary for the mixtures of this invention to limit or eliminate
flammability, but rather, these bromine containing compounds were
identified by the mere virtue of their solubility parameter and other
properties that have made them suitable in mixtures as replacements for
CFC-113.

[0084]In using the methods taught by this invention, we have also
discovered that a particularly preferred solvent replacements for CFC-113
based on solvency, ODP, boiling point, and toxicity, are those with 1
bromine atom. Compounds with multiple Br atoms were considered by the
methods taught in this invention, but these compounds could not meet most
of the required performance properties. Hence, we conclude that compounds
containing more than one bromine atom will most likely be unsuitable as
CFC-113 replacements.

[0085]We have also discovered that many of the compounds identified have
similar or better LD50, mutagenicity and genotoxicity relative to
CFC-113. Hence, combinations of these compounds will likewise have
similar or better toxicity profiles. For example, the compounds
4-bromo-3-chloro-3,4,4-trifluoro-1-butene, 1-chloro-2,2,2 trifluoroethyl
difluoromethyl ether, 2-chloro-1,1,2-trifluoroethyl difluoromethyl ether,
and methyl 2,2,2-trifluoroethyl-1-(trifluoromethyl)ether have LD50
values of >40 g/kg, 8.1 g/kg, 13 g/kg, and >40 g/kg, respectively,
compared to CFC-113 which has a value of 43 g/kg, all values being in a
range considered to be a relatively low toxicity. These same compounds
also have been found to be negative for the Ames mutagenicity assay, and
not genotoxic using in vitro Chinese hamster oocytes. CFC-113 also is
reported negative for the Ames test. Skin irritation is also an important
consideration for a solvent. The compounds
4-bromo-3-chloro-3,4,4-trifluoro-1-butene, 1-chloro-2,2,2 trifluoroethyl
difluoromethyl ether, 2-chloro-1,1,2-trifluoroethyl difluoromethyl ether,
and methyl 2,2,2-trifluoroethyl-1-(trifluoromethyl)ether have been tested
and determined to be a moderate to non-irritants, whereas CFC-113 is
listed as a mild irritant. Hence, this invention offers improvement in
some categories of toxicity compared to CFC-113. Some of the ether
compounds of this invention are also used as anesthetics or anesthetic
intermediates, and consequently, have undergone a considerable amount of
toxicity testing by the medical community.

[0086]Solvents used in oxygen handling systems, more particularly liquid
oxygen system, must not pose any risks caused by mechanical impact. We
have found that many of the compounds taught by this invention can be
combined to produce a mixture that is liquid oxygen-compatible solvent
even when the individual components may not be compatible. For example,
the compound (A) 4-bromo-3-chloro-3,4,4-trifluoro-1-butene does not pass
ASTM G86 for ignition sensitivity to mechanical impact in liquid oxygen,
but when combined with the compound (B) 1-chloro-2,2,2-trifluoroethyl
difluoromethyl ether at 25% to 50%
4-bromo-3-chloro-3,4,4-trifluoro-1-butene, the mixture passes the impact
test. This result and the observed synergy were unexpected.

[0087]Furthermore, many of the compounds taught by this invention and
found to posses superior solvency properties have previously been used as
anesthetics or are intermediates to producing anesthetics. These
compounds have been extensively tested for toxicity and mutagenicity and
pose minimal risk with regard to health. Examples of these halogenated
ether compounds include, but are not limited to, isoflurane, enflurane,
desflurane, sevoflurane, and methoxyflurane. We have also found that the
anesthetics, isoflurane (1-chloro-2,2,2-difluoroethyl difluoromethyl
ether), enflurane (2-chloro-1,1,2-trifluoroethyl difluoromethyl ether),
sevoflurane (fluoromethyl 2,2,2-trifluoro-1-(trifluoromethyl)ethyl
ether), and methyl 2,2,2-trifluoroethyl-1-trifluoromethyl ether, an
intermediate in the production of sevoflurane, have additional advantages
with respect to solvency and boiling point. These compounds have not been
previously considered as solvents in combination with other compounds.

[0088]Furthermore, we have discovered that many of the compounds which
exhibited the best cleaning performance were compounds having a linear
structure with a non-polar portion of the molecule on one end and a high
electron density on the other, or having a highly branched structure, or
having a very asymmetric structure. This feature could result from either
branching on one end or large halogen molecules on one end. Example
compounds with these characteristics are
4-bromo-3,3,4,4-tetrafluoro-1-butene,
4-bromo-3-chloro-3,4,4-trifluoro-1-butene, and methyl
2,2,2-trifluoroethyl-1-(trifluoromethyl)ether. Many of the other
compounds listed in Table 1, for example, exhibit these features.

[0089]One preferred embodiment of this invention are solvents blends
comprised of 4-bromo-3-chloro-3,4,4-trifluoro-1-butene and
1-chloro-2,2,2-difluoroethyl difluoromethyl ether, where the weight
percentage of 4-bromo-3-chloro-3,4,4-trifluoro-1-butene in the mixture
varies between about 5 wt. % and about 75 wt. %. We have found that
combinations of these 2 solvents provide exceptional cleaning performance
in several applications including oxygen handling systems cleaning, and
refrigeration system flushing.

EXAMPLES

Example 1

[0090]A sample comprising 25 volume percent (A.)
4-bromo-3-chloro-3,4,4-trifluoro-1-butene and 75 volume percent (B.)
1-chloro-2,2,2-trifluoroethyl difluoromethyl ether was added to several
beakers, each containing a metal coupon completely coated with one of the
following materials: Mil Spec 83282 hydraulic oil, Mil Spec 7808 engine
oil, Krytox fluorocarbon grease and Mil Spec 81322 aviation grease. Two
batches were subjected to 15 minute immersion with 15 mL of solvent
mixture but one was exposed to ultrasonic vibrations and the other kept
static. Afterwards, the coupons were removed and weighed for gravimetric
analysis. Results presented as percent (%) contaminant removed are shown
in Table 2 below.

[0093]Compounds having similar solubility parameter and boiling point
relative to CFC-113 (solubility parameter of 7.2, boiling point of
47.6° C.) were selected using QSPR's. Table 1 summarizes these
properties for some of the currently preferred compounds. The units for
solubility parameter are (cal/cm3)1/2.

[0094]The compounds were also required to have ODP's of less than 0.02 to
be unclassified by EPA as a Class II Ozone Depleting Substance. The
toxicity of the compounds as described by a 2 hr or 4 hr LC50 value,
and cardiac sensitization was also used as a criteria for selection. A
list of compounds were compiled and ranked which met these requirements.
If one of these critical performance properties was not known, it was
calculated or predicted using QSPR's mathematical models. A total of 30
compounds were identified with a solubility parameter within 1% of
CFC-113, and 106 compounds were identified with solubility parameter
within 5% of CFC-113, and 201 compounds had solubility parameters within
10% of CFC-113. Table 2 shows a list of preferred compounds meeting the
solubility parameter, boiling point and ODP restrictions.

[0095]The material compatibility of the second generation solvent must
also be comparable or better than that of the first generation solvent,
for example CFC-113. All of the identified second generation solvents
listed above had corrosion rates with aluminum 6061 and stainless steel
304 which were negligible (less than 0.001 mil/year). Elastomer
compatibility is also critical for a second generation solvent
replacement. All of the second generation solvents of the present
invention caused very little change in the mass, thickness, or diameter
of PTFE. The solvents containing no chlorine or bromine had little effect
on Buna-N, while the solvents containing chlorine and/or bromine had a
more severe effect on Buna-N. Viton and Neoprene were significantly
affected by CFC-113 and 4-bromo-3-chloro-3,4,4-tribromo-1-butene,
however, the other second generation solvents only had a minor affect on
Viton and Neoprene. EPDM-60 was significantly affected by all of the
solvents tested, with significant increases in mass, diameter.

[0096]In addition to the solubility parameter, several second generation
solvents were experimentally evaluated for solvency with contaminants
specific to oxygen handling systems. These contaminants were Krytox and
Jet Lube. The solvent CH2═CH--CF2--CF2Br
(4-bromo-3,3,4,4-tetrafluoro-1-butene), had solvency performance similar
to CFC-113 with both contaminants. Five solvent candidates,
CH3--CH2--O--(CF2)3--CF3,
CHF2--O--CHCl--CF3, CHClF-CF2--O--CHF2
CF3--(CF2)2--O--CHF--CF3, and
CH3--O--(CF2)3--CF3, had solvency performance as good
or better than CFC-113 with Krytox, but had poor performance with Jet
Lube. Conversely, one solvent candidate,
CH2═CH--CFCl--CF2Br, had solvency performance similar to
CFC-113 with Jet Lube, but had poor performance with Krytox.

Example 5

[0097]Mineral oil is used in R-22 refrigeration systems. To clean these
systems, a flushing solvent must be capable of quickly dissolving
residual mineral oil and other contaminants or decomposition products
that form during compressor failure. Solvent mixtures comprising (1) 50
wt. % A plus 50 wt. % B, (2) 75 wt. % A plus 25 wt. % B, and (3) 33.3 wt.
% A plus 33.3 wt. % B plus 33.3 wt. % C were produced, where (A.) is
4-bromo-3-chloro-3,4,4-tribromo-1-butene, (B.) is
1-chloro-2,2,2-trifluoroethyl difluoromethyl ether, (C.) is
2-chloro-1,1,2-trifluoroethyl difluoromethyl ether, and (E.) is methyl
2,2,2-trifluoroethyl-1-(trifluoromethyl)ether. The mineral oil was heated
in a vessel with R-22 using a torch to decompose it and form byproducts
and residue which would be formed during a compressor burnout. This
burnout oil was then applied to several metal coupons. The three solvent
mixtures above were then added to separate beakers each containing one of
the coupons. The coupons were subjected to 15 minute immersion with 15 mL
of solvent mixture under static conditions at ambient temperature.
Afterwards, the coupons were removed and weighed for gravimetric
analysis. We found that 100%, 98.6%, and 99.3% of the compressor burnout
oil was removed by solvent mixtures 1, 2, and 3, respectively.

Example 6

[0098]Alkylbenzene oil is also used in R-22 refrigeration systems. To
clean these systems, a flushing solvent must be capable of quickly
dissolving residual alkyl benzene oil and other contaminants or
decomposition products that form during compressor failure. Solvent
mixtures comprising (1) 50 wt. % B plus 50 wt. % D, and (2) 25 wt. % A
plus 75 wt. % C were produced, where (A.) is
4-bromo-3-chloro-3,4,4-tribromo-1-butene, (B.) is
1-chloro-2,2,2-trifluoroethyl difluoromethyl ether, (C.) is
2-chloro-1,1,2-trifluoroethyl difluoromethyl ether, and (D.) is
1-bromo-2-(trifluoromethyl)-3,3,3-trifluoropropene. The alkylbenzene oil
was heated in a vessel with R-22 using a torch to decompose it and form
byproducts and residue which would be formed during a compressor burnout.
This burnout oil was then applied to several metal coupons. The two
solvent mixtures above were then added to separate beakers each
containing one of the coupons. The coupons were subjected to 15 minute
immersion with 15 mL of solvent mixture under static conditions at
ambient temperature. Afterwards, the coupons were removed and weighed for
gravimetric analysis. We found that 99.4% and 99.2% of the compressor
burnout oil was removed by solvent mixtures 1, and 2, respectively. Table
5 below summarizes the cleaning performance for the mixtures of Examples
5 and 6.

[0099]As described in Example 5, several mixtures of solvents were
prepared and tested with residual mineral oil and other contaminants or
decomposition products that form during compressor failure. Solvent
mixtures comprising 1 wt. % A, 89 wt. % B, and 10 wt. % E, where (A.) is
4-bromo-3-chloro-3,4,4-trifluoro-1-butene, (B.) is 1-chloro-2,2,2
trifluoroethyl difluoromethyl ether, and (E.) is methyl
2,2,2-trifluoroethyl-1-(trifluoromethyl)ether. The solvent mixture was
then added to beakers containing a metal coupons. The coupon was
subjected to a 15 minute immersion with 15 mL of solvent mixture under
static conditions at ambient temperature. Afterwards, the coupon was
removed and weighed for gravimetric analysis. We found that 88% of the
compressor burnout oil contaminant was removed.

Example 8

[0100]Combinations of 4 solvents ((A.)
4-bromo-3-chloro-3,4,4-trifluoro-1-butene, (B.) 1-chloro-2,2,2
trifluoroethyl difluoromethyl ether, (C.) 2-chloro-1,1,2-trifluoroethyl
difluoromethyl ether, and (E.) methyl
2,2,2-trifluoroethyl-1-(trifluoromethyl)ether) were tested for mineral
oil burned in the presence of R-22. Solvents A, B, C, and E were varied
in composition between 0-6 wt. %, 80-95 wt. %, 0-10 wt. %, and 0-5 wt. %,
respectively. The solubility of these solvent mixtures was measured when
contacting the oil and residue for 1, 5, and 10 minutes with the burned
mineral oil contaminant. A composition of 13.6 wt. % A and 86.4% B was
found to remove 98.8% of the residue in 1 minute, and performed better
than the other combinations for this particular residue. Results for
different combinations are shown in Table 6 below.

[0102]The flash point temperature was measured using ASTM method D-93 on
several compounds and mixtures selected using the method of this
invention. For compounds (A.) 4-bromo-3-chloro-3,4,4-trifluoro-1-butene
(CH2═CH--CFCl--CF2Br), (B.) 1-chloro-2,2,2 trifluoroethyl
difluoromethyl ether (CHF2--O--CHCl--CF3), (C.)
2-chloro-1,1,2-trifluoroethyl difluoromethyl ether
(CHClF-CF2--O--CHF2), (D.)
1-bromo-2-(trifluoromethyl)-3,3,3-trifluoropropene
(CHBr═C(CF3)2), and (E.) methyl
2,2,2-trifluoroethyl-1-(trifluoromethyl)ether
(CH3--O--CH(CF3)2), no flash point was observed up to
their respective boiling points.

[0103]Flashpoints for mixtures of 4-bromo-3-chloro-3,4,4-trifluorobutene
and 1-chloro 2,2,2 trifluoroethyl difluoromethyl ether were also measured
where the concentrations of the components were 25-75%
4-bromo-3-chloro-3,4,4-trifluorobutene. No flashpoints were measured.

Example 11

[0104]Solvency tests with 50% by volume
4-bromo-3-chloro-3,4,4-trifluorobutene and 50% by volume ethyl
nonafluorobutyl ether were performed. The solvency characteristics of
these mixtures matched or exceeded that of CFC-113 with Krytox and Jet
Lube. The solvency of the individual components was inferior to that of
CFC-113 toward Krytox and Jet Lube, illustrating the effectiveness of
using mixtures as taught by this invention. Similarly, mixtures of
4-bromo-3,3,4,4-trifluorobutene and methyl nonafluorobutyl ether produced
solvency characteristic that met or exceeded those of CFC-113.

Example 12

[0105]The compound ethyl perfluorobutyl ether (solubility parameter of
6.69) has been measured to provide excellent solvency toward Krytox, and
the compound 1-chloro-2,2,2-trifluoroethyl difluoromethyl ether
(solubility parameter of 7.61) provides solvency of Mil-spec 83232
hydraulic fluid, Mil-spec 7808 engine oil, and Mil-spec 81322 aviation
grease. Mixtures of these ethers with about 25-75% by volume ethyl
perfluorobutyl ether will provide solvency of a broad range of
contaminants, improved over that of CFC-113, since CFC-113 is not a good
solvent for Krytox, or Mil-spec 81322 aviation grease.

Example 13

[0106]The compound methyl perfluorobutyl ether (solubility parameter of
6.75) has been measured to provide excellent solvency toward Krytox, and
the compound 2-chloro-1,1,2-trifluoroethyl difluoromethyl ether
(solubility parameter of 7.71) provides solvency of Mil-spec 83232
hydraulic fluid and Mil-spec 7808 engine oil. Mixtures of these ethers
with about 25-75% by volume methyl perfluorobutyl ether will provide
solvency of a broad range of contaminants, improved over that of CFC-113,
since CFC-113 is not a good solvent for Krytox.

Example 14

[0107]The compound 4-bromo-3-chloro-3,4,4-trifluoro-1-butene (solubility
parameter of 7.757) has been measured to provide excellent solvency
toward Mil-spec 83232 hydraulic fluid, Mil-spec 7808 engine oil, Mil-spec
81322 aviation grease, and Simple Green aqueous cleaner, and the compound
2-chloro-1,1,2-trifluoroethyl difluoromethyl ether (solubility parameter
of 7.71) provides solvency of Krytox in an ultrasonic bath and moderate
solvency of Simple Green aqueous cleaner. Mixtures of these compounds
with about 25-75% by volume 4-bromo-3-chloro-3,4,4-trifluoro-1-butene
will provide solvency of a broad range of contaminants, improved over
that of CFC-113, since CFC-113 is not a good solvent for Krytox.

Example 15

[0108]The compounds methyl 2,2,2-trifluoroethyl-1-trifluoromethyl ether,
1-chloro-2,2,2-trifluoroethyl difluoromethyl ether,
2-chloro-1,1,2-trifluoroethyl difluoromethyl ether, 25%
4-bromo-3-chloro-3,4,4-trifluoro-1-butene and 75%
1-chloro-2,2,2-trifluoroethyl difluoromethyl ether, and 50%
4-bromo-3-chloro-3,4,4-trifluoro-1-butene and 50%
1-chloro-2,2,2-trifluoroethyl difluoromethyl ether were subject to
ignition sensitivity to mechanical impact in liquid oxygen per ASTM G86.
These compounds passed this compatibility test. The compound
4-bromo-3-chloro-3,4,4-trifluoro-1-butene alone did not pass the test.
This example illustrates the unexpected benefits of using an ether such
as 1-chloro-2,2,2-trifluoroethyl difluoromethyl ether in mixtures with
compounds which may not alone be a suitable solvent for oxygen handling
systems.

Example 16

[0109]The compounds (A) 4-bromo-3-chloro-3,4,4-trifluoro-1-butene and (B)
1-chloro-2,2,2-trifluoroethyl difluoromethyl ether, were mixed 50:50 by
volume and tested to remove Krytox. The individual components, A and B,
remove 17.0% and 98.7%, respectively, of this contaminant after 15 min.
with ultrasonic treatment. The mixture removed 99.3% of the same
contaminant under the same conditions. Hence, the mixture removes more of
the contaminant than either of the individual compounds.

[0110]Although the invention has been described and illustrated in detail,
it is to be clearly understood that the same is by way of illustration
and example, and is not to be taken by way of limitation. The spirit and
scope of the present invention are to be limited only by the terms of the
appended claims.